Circuit breaker



w. lr. ALLEN CIRCUIT BREAKER Filed .July 9, 1937 May 16, 1,939.

Patented May 16, 1939 CIRCUIT BREAKER Wallace T. Allen, Royal Oak, Mich., assignor to Square D Company, Detroit, Mich., a corporation of Michigan Application July s, 1937, serial No. 152,702

6 Claims.

lThis invention relates to apparatus for making and breaking electric circuits and more particularly to means for sealing the handle opening of an automatic electric circuit breaker.

'I'he object of this invention is to provide an automatic electric circuit breaker comprising an enclosure and an opening in the enclosure through which the operating handle projects with athin flexible sheet effectively preventing the egress of arc gases through the opening about the handle.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and the appended drawing illustrating certain preferred embodiments of the invention in which:

Figure 1 is a side elevational view oi the circuit breaker according to the present invention with the side of the enclosed construction cut away to show` the interior of the breaker mechanism and with the parts in closed circuit position.

Figure 2 is a partial sectional view on the line II-II of Figure l.

The circuit breaker mechanism illustrated in the drawing follows that shown and described in the copending application of John G. Jackson and Wallace'T. Allen, Serial No. 12,798, filed March 25, 1935. 'I'his illustrates but one form of circuit breaker to which the present invention may be applied: although it isobvious that the handle seal is susceptible to use in almost any type of circuit breaker.

The circuit breaker illustrated has an enclosing structure comprised of a base I and cover 2. The

top of the cover is provided with a slot 3 through which extends an operating knob 4. The base I is in the form of a shallow cup in which, at opposite ends, are disposed stationary contacts 5, 8. Contact 5 is secured to a conducting connector l leading to the exterior of the enclosure. Contact 6 is rigidly connected to one leg of a U-shaped bimetallic member 8, to the other leg of -which is secured a conducting connector 3 leading to the exterior of the breaker. An insulating sheet II separates contact 6 from the connector 9. An arc suppressor I2 and shield I3 are disposed over each of the contacts 5 and 6.

On a bracket I4 rigidly secured to the base I adjacent the top thereof is pivotally mounted a carrier I5. Upon this carrier, intermediate its ends, are pivotally mounted a pair of plates Ii disposed on opposite sides of the carrier. A conducting bar I1 has an integral nger I l extending from the midportion thereof which is pivotally supported on theplates I3 by the pivot I3 which also serves to join the plates I3 together 6o stationary contacts 5 and 3.

(Cl. 20o-168) 'I'he plates I6 are equipped with parallel notches 2I in which is located a flipper 22 having parallel legs which are disposed in the notches on opposite sides of the conducting bar Il. The ends of the flipper legs are joined by a, cross bar 23 to which a pair of' operating springs 24 are connected.

A U-shaped operating member 25 is fulcrumed in grooves 26 in the bottom of the cup-shaped base I. The legs of the U are extended at 21 and are joined together by a pin 28 to which the ends of the operating springs 24 are secured. The member 25 has a shield 3| rigidly secured thereto which carries the operating knob 4 and closes opening 3 in the cover.

The carrier I5 is provided with a surface 29 which is engaged by the pin 28 for resetting the breaker after automatic operations'. The carrier is provided at its free end with a latching surface 32 normally engaged by a latch 33 which is pivotally carriedby the supporting plate 34 and is biased toward latching position by spring 35. The latch 33 has a portion thereof provided with an adjustable insulating abutment 36 which is disposed on the low expansion side of the bimetal in a position to be engaged thereby when;

the bimetal bends due to excess current. Open-l ings 3'I in the opposite ends of the breaker enclosure are provided for the venting of arc gases.A

The parts as shown are in the closed circuit position. To open the contacts manually the -handle 4`is moved clockwise, thus carrying the springs 24 in the same direction until the flipper .22,moves to the opposite side of the slot quickly carrying the springs past the dead center position of the bell crank formed by the plates I6 whereupon the conducting bar I l is quickly snapped to open position; To manually close the moved to the right whereupon the pin 28 engages'silrface' 29 and moves the latching surface 32 into position to be engaged by the latch .33. The parts will then be in normal on position and the operation to "on position will be as previously described.

The present invention relates particularly to the means for. sealing the opening 3 in the cover to prevent the blowing out of arc gases at the opbreaker the handle 4 is then moved in the oppoerating handle. This is accomplished by means of a thin' nexlble sheet 'as provided with an opening sliding over the operating knob 4 and thus disposed on the operating handle for movement therewith. The dimensions of the circuit breaker parts aresuch that the sheet 38 disposed between the shield 3| and the under surface 'of the cover 2 is pressed rather closely against the under surface of the cover. As more particularly shown in Figure 2 the under surface of the cover has been notched out to rather closely receive the sheet 38 in width although it is understood that this additional notching is not essential but that the flexible sheet may bear` against the under surface proper of the cover.

The flexible sheet 38 may be formed of a phenolic compound such as that known to the trade as Bakelite or may be formed of fibre or any other desired material, the essential characteristic being its exibility. In operation, when the circuit breaker interrupts relatively heavy arcs considerable gas pressure is generated within the interior of the circuit breakerand this pressing against the exible sheet 38 serves to form an effective seal against the blowing out of arc gases and these make their way through the vents 31 provided therefor. As such heavy arcs may be broken while the operating knob 4 is engaged by the hand of an operator it is highly desirable that the gases from the arc be prevented from blowing out at the handle as this might cause severe burns. With the provision of the thin flexible sheet at the -handle opening which is pressed against the bottom surface of the cover by the arc gases an effective seal is provided minimizing the possibility of arc gases venting at the handle opening and reducing possible hazard to the operator.

While certain perferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What isclaimed is:

i l. AIn an automatic electric circuit breaker having relatively movable contacts ,and automatic and manual means for effecting relative movement between said contacts, an` enclosure for said contactsand means having an opening through which a manual operator extends, and a thin, flexible member movable with said operator and disposable against an inside surface about said opening by the pressure of gases generated with- `in the enclosure by an arc drawn between said volume so that pressure is developed therein by the gases generatedl by the drawing of heavy arcs between said contacts, which pressure tends to relieve itself by the blowing out of arc gases at said operator opening, and a thin, kflexible member disposed adjacent an inside surface of said; enclosure, overlapping said opening -and movable with the manual operator, said member being pressed against said surface by saidpressure to seal the opening against egress of arc gases.

3. In an automatic electric circuit breaker hav- 'ing relatively movable contacts and manual and automatic means for effecting relative movement between said contacts, an enclosure for said contacts and means having an opening therein for the reception of a manual operator, said manual means including a manual operator extending through said opening and movable to effect manual operation of said contacts, and a' thin, exible member disposed adjacent an inside surface of said enclosure about said opening and adapted to be pressed against said sulface by gas pressure formed within the enclosure by arcs drawn between said contacts, said member being movable with said manual operator and substantially overlapping said opening over the entire range of operating movement of said operator.

4. In an automatic electric circuit breaker having relatively movable contactsand automatic and manual means for effecting relative movement between said contacts, an enclosure for said contacts and means having an opening therein through which an operating handle extends, said enclosure having a relatively restricted volume so that considerable pressure is developed therein by the gases generated by the drawing of heavy arcs between said contacts and a tendency exists for the blowing out of arc gases through said handle opening, and a, thin, flexible sheet mounted on and movable with said handle and adapted to be pressed against an interior surface of said enclosure by the developed pressure to effectively seal'the handle opening against egress of the arc gases.

5. In an automatic-electric circuit breaker having relatively movable contacts and manual and automatic means for effecting relative move ment between said contacts, said manual means including an operating handle, an enclosure for said contacts and means having an elongated opening through which said handle extends and within which it is movable to effect the manual operation of said contacts, an elongated notch in the interior surface of the enclosure about said opening, and an elongated, thin, flexible member mounted on and movable with said handle and having a width closely corresponding to the width `between vsaid contacts, said manual means including an operating handle, an enclosure for said contacts and means having an elongated opening through which said handle extends and within which it is movable to eifectthe manual operation of said contacts, said handle including a rigid and the interior surface of said enclosure about said opening, .saidmember being pressedagainst saidl surface bythe pressure of arc gases generated within the enclosureto seal-.the opening lagainst egress of the-arc gases. f

WALLACE T. f 

